Last year, I had a similar problem on my Citroen Dispatch. Talking to a trusted colleague who has a much better understanding than I do about these matters, he told me that manufacturers were pressured into replacing the asbestos content of brake pads/linings with someting more "friendly". The modern alternatives perform as well but unfortunately, the wear rate on pads but more especially discs, is greater. Discs lasting less than 20k, dependent on driving style, is not uncommon.
I paid £200ish for new front discs and pads with an Authorised Citroen Dealer.
BEWARE New pads and discs can take upto about 50 miles to bed in and attain maximum feel and power. If you do it yourself, from my experience with bikes, get some brake cleaner and keep those brake pistons immaculately clean.
Safe and happy braking

Ken